dirstate-tracked-key: update the config value to match latest discussion
Special cases are not special enough, we align the option name on the other.
The `version` value is undocumented for now as it can only have a single value.
It is supported in the code to properly detect and abort if more value are
introduced in the future value.
Differential Revision: https://phab.mercurial-scm.org/D12184
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls -A
.hg
a
unknown